Multi-cylinder internal combustion engine using exhaust gases to increase cylinder filling

ABSTRACT

Multi-cylinder internal combustion engine using exhaust gases to increase cylinder filling comprises cylinders ( 10 ) with pistons ( 2 ), a head ( 1 ) with lifting valves ( 7 ) and a crankshaft mechanism ( 3 ) and is provided with two cylinders ( 10 ) with mutually shifted four-stroke cycle and/or is provided with three cylinders ( 10 ) with mutually shifted four-stroke cycle and in the head ( 1 ) of each cylinder ( 10 ) there is at least one intake port ( 5 ) interconnected with at least one exhaust port ( 6 ) and at least one lifting valve ( 7 ), while the intake port ( 5 ) is provided with at least one valve ( 8 ) and an exhaust branch ( 9 ) is connected to the exhaust port ( 6 ) and simultaneously exhaust branches ( 9 ) of two cylinders ( 10 ) with mutually shifted cycle are farther joined in a joint ( 11 ) into one cross-section and/or exhaust branches ( 9 ) of three cylinders ( 10 ) with mutually shifted cycle are farther joined in another joint into one cross-section.

TECHNICAL FIELD

This invention relates to an arrangement of a four-stroke multi-cylinderinternal combustion engine. It relates particularly to valves in acylinder head and to an embodiment of an intake and exhaust manifold, sothat higher volumetric efficiency of the cylinder as well as higheroverall efficiency of the combustion engine is reached, by means of thedirect use of a part of energy of exhaust gas pressure waves in theexhaust manifold.

BACKGROUND OF THE INVENTION

Current modern four-stroke piston engines work usually with amulti-valve gear mechanism in a cylinder head. Intake valves with intakeports are placed in one part of the cylinder head and exhaust valveswith exhaust ports are placed in the other part of the cylinder head. Itis possible to use energy of exhaust gases for a better cylinderfilling, but only to a limited extent. Suitably designed exhaustmanifold as well as intake manifold and appropriate valve timing canensure scavenging of a combustion chamber of the cylinder and set intakegas in motion in the intake port. It results in a small improvement incylinder filling by intake gas. Further, engine efficiency can beinfluenced by exhaust manifold, which uses flow momentum of exhaustgases in the manifold and enables easier discharge of exhaust gases outof the cylinder. That leads to a decrease of the pumping workparticularly during the exhaust stroke. That is all about direct usingof energy of exhaust gases for cylinder filling and for increase ofefficiency of current engines. Direct use of energy of exhaust gases bymeans of Comprex system is not as advantageous as a turbocharger.Supercharging by turbocharger is widely spread way of use of exhaust gasenergy. Even in this case, there is a loss of energy by transferringenergy of exhaust gases to a turbine. It is caused by a differencebetween cyclic work of a piston engine and continual work of a turbine.In the past there have been systems that tried to use the pressure waveof exhaust gas directly to improve cylinder filling, for instance byinterconnecting intake manifold with exhaust one. Those solutions aredescribed for example in GB592995A, DT2328692A1, JP58104325A,JP61237824A, DE3137454A1, DE3137471A1 and WO0153677A1. Efficiency oftheir function was not sufficient and they did not break through.

SUMMARY OF THE INVENTION

Above mentioned deficiencies are removed to a certain extent in amulti-cylinder internal combustion engine with use of exhaust gaspressure to increase cylinder filling. That engine consists of cylinderswith pistons, a cylinder head with lifting valves and a crankshaftmechanism. The essence of the engine is the fact that it is equippedwith two cylinders that have mutually shifted four-stroke cycle and/orit is equipped with three cylinders that have mutually shiftedfour-stroke cycle. In the cylinder head of each cylinder is at least oneintake port, connected with at least one exhaust port and at least onelifting valve, while the intake port is equipped with at least one valveand an exhaust branch is connected to the exhaust port andsimultaneously exhaust branches of both cylinders with mutually shifted4-stroke cycle are farther joined in a joint into one cross-sectionand/or exhaust branches of three cylinders with mutually shiftedfour-stroke cycle are farther joined in another joint into onecross-section.

Lifting valves have both intake and exhaust function.

A valve of the intake port is advantageously in the shape of a rotaryvalve and/or in the shape of a reed valve.

The valve of the intake port can be equipped with electronic control.

An intake manifold is advantageously connected to the intake port. Thisintake manifold is equipped with a centrifugal compressor and/or with apositive displacement compressor that is mechanically connected to theengine and/or equipped with an electric motor.

There can be placed an exhaust valve and/or an exhaust outlet pipebehind the joint of two exhaust branches and/or behind another joint ofthree exhaust branches.

There can be placed a turbine of a turbocharger behind the joint of twoexhaust branches and/or behind another joint of three exhaust branchesand there is a compressor of the turbocharger in the intake manifold,while the exhaust outlet pipe joins outlet of the turbine of theturbocharger.

In advantageous embodiment, the multi-cylinder internal combustionengine comprises more cooperating cylinder pairs with mutually shiftedfour-stroke cycle and with joints of exhaust branches and/or itcomprises more cooperating cylinder trios with mutually shiftedfour-stroke cycle and with other joints of exhaust branches.

The multi-cylinder internal combustion engine can consist of morecooperating cylinder pairs with mutually shifted four-stroke cycle andwith joints of exhaust branches and/or it can consist of morecooperating cylinder trios with mutually shifted four-stroke cycle andwith other joints of exhaust branches, while joints and/or other jointsare farther connected to separate sections of inlet housing of a turbineof a turbocharger.

The lifting valve has a valve head in the annular shape in anadvantageous embodiment.

Four-stroke internal combustion engine according to the inventionenables an improvement of engine performance parameters, decrease of itsspecific mass as well as decrease of its specific fuel consumption. Thatis achieved for two reasons.

The first important reason for an increase in engine parameters isdirect use of a part of exhaust gas energy. That is enabled due to theengine arrangement with interconnected intake and exhaust port in thecylinder head and appropriate tuning of the whole system of a valve gearand engine manifold. Briefly, the difference between operation of themulti-cylinder engine according to the invention and operation of atraditional four-stroke cycle is in intensive scavenging of the cylinderhead at the end of the exhaust stroke, taking gas in during the intakestroke also in the exhaust branch besides the cylinder and subsequentrefilling of the gas into the cylinder by means of pressure of exhaustgas. Described effect can be achieved only in such an engine with two orthree cooperating cylinders of the engine. A part of energy of theexhaust pressure wave is used directly for compressing intake gas intothe cylinder and so it is possible to reach significantly highercylinder filling. That increases mean effective pressure of the engineas well as its efficiency. A naturally aspirated variant of the engineaccording to the invention in one configuration of valve timing andpipes geometry has excellent parameters in a relatively narrow range ofengine speed. That does not have to be disadvantage in case of usingthis engine at a generator. The absence of a turbocharger and relatedturbo lag increasing time required for run-up till the full power can bean advantage in this case, in comparison with a traditional engine withsimilar performance and dimensions. Four-stroke combustion engineaccording to the invention in turbocharged version achievescharacteristic suitable for a common driving cycle with excellentparameters in the whole engine speed range and it is useable in currentvehicles.

The second reason for an increase in engine parameters is the fact thatthe cylinder head can be equipped with a lifting valve or valves in itsentire area and thus the passable area for valve increases. It is betterto use all lifting valves simultaneously as intake and exhaust. Decreasein throttling in valves in the cylinder head causes decrease of lossesby drawing gas into the cylinder and further the pumping work isdecreased, while useable energy of exhaust gases is increased at thesame time. The most advantageous is using a lifting valve with a valvehead in the annular shape that has both intake and exhaust function.This valve enables to achieve the best flow parameters in intakedirection into cylinder, exhaust direction from cylinder as well as indirection of scavenging the cylinder head. The use of shared liftingvalves for intake and exhaust that are placed in the entire area of thecylinder head has further advantages. The cylinder head and liftingvalves are significantly less thermally stressed due to the changing ofintake and exhaust period. There will be no creation of solid sedimentsdue to the lower temperatures on the valve and valve seats and a higherdurability of valves, seats and engine heads will be achieved.Possibility of use of internal exhaust gas recirculation in part andfull load of the engine can be another advantage. Higher air excess inexhaust gases can be used for its better oxidation. It is possible todecrease emissions of the engine by use of those possibilities and theircombinations.

BRIEF DESCRIPTION OF THE DRAWINGS

A multi-cylinder internal combustion engine supercharged by exhaustgases according to the invention will be closer clarified in exemplaryembodiment with the help of enclosed figures.

FIG. 1 schematically shows a multi-cylinder combustion engine with twocylinders with a four-stroke cycle that is mutually shifted about 360.There are cyclically working valves in the intake ports and exhaustbranches of both cylinders are joined into one exhaust outlet pipe.

FIG. 2 schematically shows a multi-cylinder internal combustion enginewith two cylinders with a four-stroke cycle that is mutually shiftedabout 360, similarly to the FIG. 1. The difference is that the intakeport is equipped with a rotary valve and a reed valve and there is anexhaust valve in the shape of an exhaust rotary valve behind the jointof exhaust branches.

FIG. 3 schematically shows a multi-cylinder internal combustion enginewith two cylinders with four-stroke cycle that is mutually shifted about360, similarly to the FIG. 1. The difference is that the intake port isequipped with a reed valve and there is a centrifugal compressor in theintake port.

FIG. 4 schematically shows a multi-cylinder internal combustion enginewith two cylinders, similarly the FIG. 2. The difference is that thereis a positive displacement compressor in the intake manifold.

FIG. 5 schematically shows a multi-cylinder internal combustion enginewith two cylinders, similar to the FIG. 3. The difference is that behindthe joint of exhaust branches there is a turbine of a turbocharger and acompressor of the turbocharger is situated in the intake manifold.

FIG. 6 schematically shows a multi-cylinder internal combustion enginewith two cylinders with a cycle that is shifted about 360. That engineis equipped with a turbocharger, similarly to the FIG. 5. The differenceis that even a rotary valve is placed in the intake port besides thereed valve.

FIG. 7 schematically shows a multi-cylinder internal combustion enginewith two cylinders with a four-stroke cycle that is mutually shiftedabout 360, similarly to the FIG. 1. An exhaust valve is additionallyplaced behind the joint of exhaust branches.

FIG. 8 graphically shows dependence of some parameters of a two-cylinderengine according to the FIG. 7. All curves are dependent on crankshaftangle that is represented by x axis. Curves IA and IIA representbehavior of a cross-sectional area of lifting valves. Curves Ip and IIprepresent behavior of pressure in exhaust ports in a cylinder head.Curve B represents behavior of a cross-sectional area of the exhaustvalve.

FIG. 9 shows a multi-cylinder internal combustion engine according tothe FIG. 7 in crankshaft angle positions from 0 to 720 in 90 intervals.That demonstrates working of the engine during the entire cycle. Intakegas is represented by gray color. Exhaust gases are not colored.

FIG. 10 shows a multi-cylinder internal combustion engine with twocylinders with a cycle that is shifted about 360, similarly to the FIG.7, in crankshaft angle positions from 0 to 720 in 90 intervals with thedifference that in the exhaust manifold there is placed a rotary valveand a reed valve is used in the intake manifold. Intake gas isrepresented by gray color. Exhaust gases are not colored.

FIG. 11 schematically shows a multi-cylinder internal combustion enginewith three cylinders with a cycle that is mutually shifted about 240.Intake and exhaust ports in a cylinder head are interconnected andlifting valves are shared for both intake into the cylinder and exhaustout of the cylinder. There are cyclically working valves in intake portsand exhaust branches of the three cylinders are joined into one outletpipe.

FIG. 12 schematically shows a multi-cylinder internal combustion enginewith three cylinders, similarly to the FIG. 11. A centrifugal blower isadditionally placed in the intake manifold.

FIG. 13 schematically shows a multi-cylinder internal combustion enginewith three cylinders, similarly to the FIG. 11. The difference is thatthe engine is equipped with a turbocharger.

FIG. 14 schematically shows a multi-cylinder internal combustion enginewith three cylinders with four-stroke cycle that is mutually shiftedabout 240 and a turbocharger, similarly to the FIG. 13. The differenceis that intake ports are equipped with reed valves and a positivedisplacement compressor is situated in the intake manifold.

FIG. 15 schematically shows a multi-cylinder internal combustion enginewith three cylinders with four-stroke cycle that is shifted about 240,similarly to the FIG. 11. The difference is that there is a positivedisplacement compressor in the intake manifold and an exhaust valve isadditionally placed behind the joint of exhaust branches.

FIG. 16 graphically shows dependency of some parameters of atwo-cylinder engine according to the FIG. 15. All curves are dependenton crankshaft angle that is represented by x axis. Curves IA, IIA andIIIA represent behavior of a cross-sectional area of lifting valves.Curves Ip, IIp and IIIp represent behavior of pressure in exhaust portsin the cylinder head. Curve B represents behavior of cross-sectionalarea of the exhaust valve.

FIG. 17 shows an internal combustion engine according to the FIG. 15 incrankshaft angle positions from 0 to 720 in 120 intervals. Thatdemonstrates the working of the engine during the entire cycle. Intakegas is represented by gray color. Exhaust gases are not colored.

FIG. 18 shows a multi-cylinder internal combustion engine with threecylinders with a cycle shifted about 240, similarly to the FIG. 17, incrankshaft angle positions from 0 to 720 in 120 intervals. Thedifference is that there is a reed valve in the intake port and theengine is not equipped with an exhaust valve. Intake gas is representedby gray color. Exhaust gases are not colored.

FIG. 19 shows a multi-cylinder internal combustion engine with fourcylinders on condition that it consists of two pairs of cooperatingcylinders. Two outlet pipes going from joints of exhaust branches areconnected to separate sections of outlet of turbine housing of a sharedturbocharger.

FIG. 20 shows a cross-sectional view of the cylinder head that isperpendicular to the cylinder axis in the view direction into thecylinder. The figure shows a valve head of the lifting valve and theintake and exhaust port.

FIG. 21 shows a cross-sectional view of the cylinder head that isperpendicular to the cylinder axis in the view direction into thecylinder. The figure shows valve heads of two lifting valves and theintake and exhaust port.

FIG. 22 shows a cross-section of the cylinder head that is perpendicularto the cylinder axis in the view direction into the cylinder. The figureshows valve heads of two lifting valves and the intake and exhaust port.

FIG. 23 shows a cross-section of the cylinder head that is perpendicularto the cylinder axis in the view direction into the cylinder. The figureshows valve heads of four lifting valves and the intake and exhaustport.

FIG. 24 shows a cross-section of the cylinder head that is perpendicularto the cylinder axis in the view direction into the cylinder. The figureshows a centrally positioned lifting valve with a valve head in theannular shape and the intake and exhaust port.

FIG. 25 shows a cross-section of the cylinder head that is perpendicularto the cylinder axis in the view direction into the cylinder. The figureshows a centrally placed lifting valve with a valve head in the annularshape and an eccentric intake and exhaust port.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The model multi-cylinder internal combustion engine supercharged byexhaust gases according to the FIG. 1 comprises two cylinders 10 withpistons 2, a cylinder head 1 with lifting valves 7 and a crankshaftmechanism 3. Two cylinders 10 have a cycle that is mutually shiftedabout ½ of four-stroke cycle. There is placed an intake port 5interconnected to an exhaust port 6 and valves 7 with both intake andexhaust function in the cylinder head 1 of each cylinder 10. The intakeport 5 is equipped with a cyclically working valve 8 and an exhaustbranch 9 is connected to the exhaust port 6. Exhaust branches 9 of bothcylinders 10 are joined into one cross-section in a joint 11 and anoutlet exhaust pipe 22 goes on from that joint.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 2 is based on the embodiment according to the FIG. 1. Avalve 8 is replaced with a rotary valve 8 a together with a reed valve 8b. There is additionally placed an exhaust valve 21 in the shape of anexhaust rotary valve behind the joint of exhaust branches 9.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 3 is based on the embodiment according to the FIG. 1. Avalve 8 is replaced with a reed valve 8 b. The engine is equipped withan intake manifold 4, in which a centrifugal compressor 13 is placed.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 4 is based on the embodiment according to the FIG. 2. Theengine is equipped with the intake manifold 4, in which a positivedisplacement compressor 14 is placed.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 5 is based on the embodiment according to the FIG. 3. Thereis a turbine 23 of a turbocharger behind the joint 11 of exhaustbranches 9 and a compressor 15 of a turbocharger in the intake manifold4.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 6 is based on the embodiment according to the FIG. 5. Thereare additionally placed rotary valves 8 a in intake ports 5.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 7 is based on the embodiment according to the FIG. 1. Thereis additionally placed an exhaust valve 21 behind the joint of exhaustbranches 9.

The model multi-cylinder internal combustion engine supercharged byexhaust gases according to the FIG. 11 comprises three cylinders 10 withpistons 2, a cylinder head 1 with lifting valves 7 and a crankshaftmechanism 3. Three cylinders 10 have a cycle that is mutually shiftedabout ⅓ of four-stroke cycle. There is placed the intake port 5interconnected to the exhaust port 6 and valves 7 with both intake andexhaust function in the cylinder head 1 of each cylinder 10. The intakeport 5 is equipped with a cyclically working valve 8 and the exhaustbranch 9 is connected to the exhaust port 6. Exhaust branches 9 of allthree cylinders 10 are joined into one cross-section in a joint 12 andthe outlet exhaust pipe 22 goes on from that joint.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 12 is based on the embodiment according to the FIG. 11. Theengine is equipped with an intake manifold 4 that is equipped with acentrifugal compressor 13.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 13 is based on the embodiment according to the FIG. 11.There is additionally placed a turbine 23 of a turbocharger behind thejoint 12 of exhaust branches 9 and a compressor 15 of the turbochargerin the intake manifold 4.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 14 is based on the embodiment according to the FIG. 13.Valve 8 is replaced with a reed valve 8 b. There is additionally placeda positive displacement compressor 14 into the intake manifold 4.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 15 is based on the embodiment according to the FIG. 11. Theengine is equipped with the intake manifold 4, in which the positivedisplacement compressor 14 is placed and there is additionally placed anexhaust valve 21 behind the joint of exhaust branches 9.

The model multi-cylinder internal combustion engine according to theFIG. 19 comprises two cooperating pairs of cylinders 10 in anarrangement according to the FIG. 1. It is equipped with a shared intakemanifold 4, in which a compressor 15 of a shared turbocharger is placed,and both joints 11 of exhaust branches 9 are connected to separatesection of inlet housing 26 of a turbine 23 of a shared turbocharger.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 20 is equipped with the head 1 of the cylinder 10. The head1 is equipped with a classic lifting valve 7.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIGS. 21 and 22 has the head 1 of the cylinder 10. The head 1 isequipped with two classic lifting valves 7.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIG. 23 has the head 1 of the cylinder 10. The head 1 is equippedwith two classic lifting valves 7.

The embodiment of a multi-cylinder internal combustion engine accordingto the FIGS. 24 and 25 has the head 1 of the cylinder 10. The head isequipped with one lifting valve 7, the head of which is in the annularshape.

The function of a multi-cylinder internal combustion engine superchargedby exhaust gases is following. A two-cylinder engine works in thefour-stroke cycle on condition that the cycle of cylinders 10 ismutually shifted about ½ of the cycle, it means 360. The first cylinder10 starts usually with ignition and subsequent expansion. The exhauststroke begins by opening lifting valves 7 in the head 1 of the firstcylinder 10 at the end of the expansion, before the bottom dead center.Valve 8 in the intake port 5 is closed and prevents flowing of exhaustgases through the intake port 5. Pressure wave of exhaust gases travelsthrough the exhaust branch 9 of the first cylinder 10 to the joint 11and from here it advances through the second exhaust branch 9 to liftingvalves 7 of the second cylinder 10. In the second cylinder 10, there isjust the intake stroke in progress. Valve 8 in the intake port 5 is ofthe second cylinder 10 is closing and gas that was drawn into theexhaust port 6 and the exhaust branch 9 before is pushed into the secondcylinder 10. Lifting valves 7 of the second cylinder 10 closesafterwards and the compression stroke can start. That causes animprovement in the filling of the second cylinder 10. The first cylinder10 finishes the exhaust stroke of the piston 2 and the pressure in theexhaust port 6 decreases at the end of the exhaust stroke. Valve 8 inthe intake port 5 of the first cylinder 10 opens and the head 1 isscavenged by gas that is drawn from the intake port 5 into the exhaustport 6 of the first cylinder 10. As the piston moves during the intakestroke, the gas is drawn into the first cylinder 10 and that gassimultaneously flows into the exhaust branch 9 of the first cylinder 10,until the exhaust pressure wave from the second cylinder 10 arrives.Valve 8 in the intake port 5 of the first cylinder 10 is subsequentlyclosed and gas previously taken into the exhaust port 6 and the exhaustbranch 9 is pushed into the first cylinder 10. Closing of lifting valves7 of the first cylinder 10 ensues and the compression stroke can start.That enables an improvement in filling of the first cylinder 10. Theprocess in the second cylinder is the same as in the first cylinder. Theengine in naturally aspirated variant will achieve excellent parametersonly in a narrow range of engine speed. The whole system tuning issignificantly influenced by all valve timing of all valves, particularlylengths and cross-sectional areas of exhaust branches 9 and outlet pipes22. It can be influenced for instance by the angle a that is an anglebetween inlets entering the joint 11 of exhaust branches 9. Considerablechange of the most advantageous engine speed in naturally aspiratedvariant is possible to reach only by the change of length of exhaustbranches 9 and of the outlet pipe 22. The work of a valve can beelectronically controlled after processing instantaneous data that areread from the engine.

Two-cylinder engine with the rotary valve 8 a and the reed valve 8 b inthe intake port 5 enables automatic and quick opening and closing of theintake port 5. The rotary valve 8 a prevents gas flowing into theexhaust branch 9 of the cylinder 10 during the compression and expansionin this cylinder 10. It actually prevents unnecessary high excess ofdrawing gas in exhaust gases of the engine. If there is the exhaustvalve 21 behind the joint 11, it is possible to increase the amplitudeof the exhaust pressure wave. The exhaust valve 21 closes the outletcross-section of the joint 11 at the time, when the pressure wave ofexhaust gases reaches this joint 11. The cross-section is subsequentlyopened in order to enable pressure decrease in exhaust branches 9. FIG.8 shows behavior of cross-sectional area IA, IIA in lifting valves 7 andpressure Ip, IIp in exhaust ports 6 of the head 1 of both cylinders10.It also shows behavior of a cross-sectional area B of the exhaustvalve 21. Behavior of a two-cylinder engine without using the exhaustvalve 21 is similar to that case with the exhaust valve 21. Just thevalues of pressures Ip and IIp are lower.

Two-cylinder engine according to the FIG. 3 with the reed valve 8 b inthe intake port 5 enables automatic and quick opening and closing of theintake port 5. The reed valve 8 b opens whenever the value of thepressure in the exhaust port 6 drops below the value of the pressure inthe intake manifold 4. That enables that the flow of intake gas into theexhaust port 6 is enabled not only during the intake into the cylinder10, but also during the compression and expansion in the cylinder 10.That can be used in case that there is a requirement of increase inamount of drawn gas in exhaust branches 9. If there is placed acentrifugal compressor 13 in the intake manifold 4, the filling ofcylinders 10 by intake gas will improve and that will cause widening ofengine speed range, in which the engine has high parameters.

Two-cylinder engine according to the FIG. 4 with the positivedisplacement compressor 14 that is placed in the intake manifold 4 andwith the exhaust valve 21 behind the joint 21 enables anotherimprovement in filling of cylinders 10 by intake gas. Influence ofdynamic of exhaust gases flow in the outlet pipe 22 on filling ofexhaust branches 9 by intake air decreases and that causes anotherwidening of the engine speed range, in which the engine has highparameters.

In case according to the FIG. 6, where a two-cylinder engine uses theturbine 23 of a turbocharger behind the joint 11 and the compressor 15of the turbocharger in the intake manifold, behavior of the engine issimilar to the naturally aspirated variant. All pressures in the engineincrease. However, it enables to reach excellent parameters of theengine in a wider range of engine speed compared to naturally aspiratedversions. In this case, there is no importance of influence of exhaustgases flow dynamic in the outlet exhaust pipe 22. Inertia of the turbine23 prevails and the turbine ensures required fluctuation of gas pressurein exhaust branches 9 in a wide range of engine speed. There isadvantageous possibility to use the turbine 23 of the turbocharger withregulation.

Gas exchange process of the cylinder 10 of the three-cylinder enginevariant is similar to two-cylinder variant. The process is infour-stroke cycle on condition that the cylinders cycle 10 is mutuallyshifted about ⅓ of the cycle (240). In the first cylinder 10, usualignition and subsequent expansion come. At the end of the expansion,before bottom dead center of the piston 2, exhaust stroke begins byopening lifting valves 7 in the head 1 of the first cylinder 10. Valve 8in the intake port 5 is closed and prevents exhaust gas flow through theintake port 5. Exhaust gas pressure wave advances through the exhaustbranch 9 of the first cylinder 10 to the joint 12 and from there, itgoes on through the second and third exhaust branch 9 to lifting valves7 of the second and third cylinder 10. There is just the intake strokein progress in the second cylinder 10. Valve 8 in the intake port 5 ofthe second cylinder 10 closes and gas previously taken into the exhaustport 6 and the exhaust branch 9 is pushed into the second cylinder 10.After that, also lifting valves 7 of the second cylinder 10 close andthe compression stroke can start. That enables to reach increase infilling of the second cylinder 10. There is compression and expansion inprogress in the third cylinder 10 and lifting valves 7 and the valve 8are closed. The first cylinder 10 finishes its exhaust stroke of thepiston 2 and pressure in the exhaust port 6 decreases at the end of theexhaust stroke. Valve 8 in the intake port 5 of the first cylinder 10opens and the head 1 is scavenged by intake gas flowing from the intakeport 5 into the exhaust port 6 of the first cylinder 10. During theintake stroke, piston 2 moves down and gas is taken into the firstcylinder 10 and simultaneously the gas is flowing even into the exhaustbranch 9 of the first cylinder 10, until a pressure wave of the exhauststroke of the third cylinder 10 arrives. Valve 8 in the intake port 5 ofthe first cylinder 10 closes and gas taken into the exhaust port 6 andthe exhaust branch 9 is pushed into the first cylinder 10. Afterwards,even lifting valves 7 of the first cylinder 10 close and the compressionstroke can start. That is how an increase in filling of the firstcylinder 10 is reached. Process of the cycle in the second and thirdcylinder 10 is the same as in the first cylinder 10.

It is possible to use a three-cylinder engine in the same variants ofengine arrangements as a two-cylinder engine version. For example, withvarious valves in the intake port 5, with the centrifugal compressor 13or with the positive displacement compressor 14 that is placed in theintake manifold 4. If there is the exhaust valve 21 behind the joint 12,it is possible to increase the amplitude of the exhaust pressure wave.The exhaust valve 21 closes inlet cross-sectional area of the joint 12at the time, when an exhaust gas pressure wave reaches this joint 12.The cross-sectional area is opened afterwards in order to enabledecrease of pressure in exhaust branches 9. In the FIG. 16, there isbehavior of cross-sectional area IA, IIA, IIIA of lifting valves 7 andpressure Ip, IIp, IIIp in exhaust ports 6 of the head lof the threecooperating cylinders 10. There is also shown behavior ofcross-sectional area B of the exhaust valve 21. Process of work of athree cylinder engine without use of the exhaust valve 21 is similar tothat in case with exhaust valves 21. Just the values of pressures Ip,IIp and IIIp are lower.

A two-cylinder variant has cooperating cylinders 10, whose cycles areshifted about ½ cycle, it means 360 and the pressure wave of exhaustgases arrives at the cylinder 10, in which the intake stroke near thebottom dead center of the piston 2 is in progress. Actually at the endof the intake stroke. The cycle shift of cooperating cylinders 10 at athree-cylinder variant is ⅓, it means 240, the exhaust pressure wavearrives at the cylinder 10, where the intake stroke is in progress,earlier than in the two-cylinder variant. To enable additional intake ofdrawing gas into the engine cylinder 10 and the exhaust branch 9 evenbefore the pushing of taken gas into the cylinder 10 by exhaust gaspressure, it is necessary to delay a pressure wave by longer exhaustbranches 9 than at a two-cylinder engine. Or it is necessary to increasepressure in the intake manifold 4, for example by the positivedisplacement compressor 14. Angle delay of the exhaust gases pressurewave increases as the engine speed increases. Generally, amulti-cylinder engine of arrangement with two cooperating cylinders 10is more advantageous rather for lower engine speed and a multi-cylinderengine of arrangement with three cooperating cylinders 10 isadvantageous rather for higher engine speed.

An engine with higher number of cylinders 10 is necessary to be solvedas a connection of more pairs or trios of cooperating cylinders 10. Theexhaust system must be lead separately from each pair and trio ofcooperating cylinders. Or it is possible to join them at the ends ofexhaust outlet pipes 22 in a sufficient distance from the engine, sothat there would be no influence of individual exhaust systems.

Particular case according to the FIG. 19 is, when a common turbochargeris used at a turbocharged engine with more pairs of cooperatingcylinders 10. Outlets of joints 11 must be connected to separate sectionof common inlet housing 26 of the turbine 23 of the common turbocharger.

There can be placed any number of lifting valves 7 in the cylinder head1 according to the FIGS. 20 to 23. These valves must enable both intakeinto the cylinder 10 and exhaust out of the cylinder 10. Therefore it isadvantageous to use them all for both intake and exhaust. In addition toall arrangements with classic poppet lifting valves 7, there is aninteresting possibility to use a lifting valve 7 with an annular valvehead according to the FIGS. 24 and 25. In addition to that that itenables to reach the best flow parameters, it is also possible toadvantageously form the intake port 5 as well as the exhaust port 6 toachieve swirl of intake gas in the cylinder 10.

Briefly, the difference between operation of a multi-cylinder engineaccording to the invention and operation of a classic four-stroke cycleis in intensive scavenging of the head 1 at the end of the exhauststroke, intake of gas during the intake stroke not only into thecylinder 10, but even in the exhaust branch 9 and subsequent pushing ofgas from the exhaust branch 9 to the cylinder 10 by pressure of exhaustgases. This effect is enabled by the cylinder head 1 that has theinterconnected intake port 5 with an exhaust port 6 and joined exhaustbranches 9 of two or three cooperating cylinders 10. Tuning of thesystem depends on many parameters. It is possible to achieve describedeffect only with an engine with two or three cooperating enginecylinders 10. If the system should be able to achieve requiredparameters, a quality realization of the head 1 with valves 8 andlifting valves 7 of low flow resistance is necessary. Low flowresistance in the direction of scavenging the head 1 from the intakeport 5 into the exhaust port 6 is particularly important. Length andcross-sectional area of exhaust branches 9 and arrangement of theirjoint 11 or 12 is crucial. Further there are influences of valve timingsettings and ways of regulation of a turbocharger. Another differencebetween an engine according to the invention and an engine with classicfour-stroke cycle is possibility of use of natural exhaust gasrecirculation in part load as well as full load of the engine. That canbe influenced by many regulations, for example by throttling in theintake port 4.

INDUSTRIAL APPLICABILITY

Multi-cylinder internal combustion engine according to the invention innaturally aspirated variant is suitable particularly for dieselarrangement for driving a generator, for example as a range extender forelectric cars. Variants of an engine according to the invention with acompressor or a turbocharger are suitable as a drive of currentvehicles. Spark ignition variant with direct injection could find use onsmall airplanes market thanks to its high specific power. Possibility ofuse as gas engines running on natural gas is also promising. It would beadvantageous to blow the gas directly into the cylinder of such anengine.

1. A multi-cylinder internal combustion engine using exhaust gases toincrease cylinder filling, the engine comprising cylinders with pistons,a head with lifting valves and a crankshaft mechanism wherein the engineis provided with two cylinders with a mutually shifted four-stroke cycleor is provided with three cylinders with a mutually shifted four-strokecycle and in the head of each cylinder there is at least one intake portthat is interconnected with at least one exhaust port and at least onelifting valve, while the intake port is provided with at least one valveand there is an exhaust branch connected to the exhaust port andsimultaneously exhaust branches of two cylinders with the mutuallyshifted four-stroke cycle are further joined in a joint into onecross-section or exhaust branches of three cylinders with the mutuallyshifted four-stroke cycle are further joined in another joint into onecross-section.
 2. The multi-cylinder internal combustion engineaccording to claim 1 wherein lifting valves have both intake and exhaustfunction.
 3. The multi-cylinder internal combustion engine according toclaim 1, wherein the valve of the intake port is in the form of a rotaryvalve or in the shape of a reed valve.
 4. The multi-cylinder internalcombustion engine according claim 1, wherein the valve of the intakeport is provided with an electronic control.
 5. The multi-cylinderinternal combustion engine according to claim 1, wherein to the intakeport there is connected an intake manifold, which is provided with acentrifugal compressor or a positive displacement compressor that ismechanically connected to the engine or provided with an electric motor.6. The multi-cylinder internal combustion engine according to claim 1,wherein an exhaust valve or an exhaust outlet pipe is placed behind thejoint of exhaust branches or behind another joint of exhaust branches.7. The multi-cylinder internal combustion engine according to claim 1,wherein behind the joint of exhaust branches or behind another joint ofexhaust branches there is a turbine of a turbocharger and a compressorof the turbocharger is placed in the intake manifold, while the exhaustoutlet pipe is connected to an outlet of the turbine of theturbocharger.
 8. The multi-cylinder internal combustion engine accordingto claim 1, wherein the engine comprises more cooperating pairs ofcylinders that have mutually shifted four-stroke cycle and that areprovided with joints of exhaust branches or more cooperating trios ofcylinders that have mutually shifted four-stroke cycle and that areprovided with other joints of exhaust branches.
 9. The multi-cylinderinternal combustion engine according to claim 1, wherein the enginecomprises more cooperating pairs of cylinders that have mutually shiftedfour-stroke cycle and that are provided with joints of exhaust branchesor more cooperating trios of cylinders that have mutually shiftedfour-stroke cycle and that are provided with other joints of exhaustbranches, while joints or other joints are further connected toseparated sections of an inlet housing of the turbine of sharedturbocharger.
 10. The multi-cylinder internal combustion engineaccording to claim 1, wherein the lifting valve has a valve head of anannular shape.